8800Gt or 3870 are great choices.
But if you're not going to be upgrading your monitor in the near future for higher res, you could go with a 3850, save some $$ and be just as happy.
I have an 19" monitor too. My old rig has a 1950Pro 512 in it and I play Witcher at the highest settings, 4AA, 12AF and stay in the 35-40fps range (very playable imho). With a 3850 you'd do even better.
Course if you've got the $$ to spend and want to future proof better, the other cards are certainly the way to go.
8800gt or 3870 or even the 8800gts 512 if you can afford it. I'd go with the e8400, since at stock speeds will get you the best gaming performance, due to the higher stock clock speeds. If your going to OC than the q6600 is nice, but the C2D's are just as good, in most situations. If you have some heavy CPU rendering to do than the q6600 would be the one to get.
i would go for 512mb. I had the 8800gts 320 and it just wasnt enough for games like crysis. i have the 8800gt 512 right now and couldn't be happier. cant go wrong with a larger frame buffer.
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